of tubize



A. DRYEN. METHOD FOR THE CONCENTRATION OF SULFURIC ACID. 1,323,847.

Patented Dec. 2,1919.-

* UNITED STATES PATEN oFIuoE.

ACHILLE DRYEN, OF TUBIZE, BELGIUM, ASSIGNOR TO SOCIETE ANQNYME FABRIQUEDE SOIE ARTIFICIELLE DE TUBIZE, OF TUBIZE, BELGIUM.

I METHOD-FOR THE CONCENTRATION OF SULFURIC ACID.

Appilcation filed June 2 5, 1915 Serial No. 36,190.

To all whom it laay concern: I

Be it known that I, AornLLn D RY EN, a subject of the King of Belgium,resldmg at Tubize,in the Kingdom of Belgium, have invented certain newand useful Improvements in Methods for the Concentration of SulfuricAcid, of which the following is a specification.

' evaporating elements which are arranged in a stepped order andcommunicate with one another in such a manner that the acid flows fromthe uppermost to the lowermost ele-.v

ment while'the vapors, which are produced by the ebullition of the acidunder the action of asource of heat acting from outside, pass from thelowermost to the uppermost element of the'series.

My invention hasfor its object to secure 'a' more perfect utilization ofthe heat contained in the vapors which are'produced,

than has been hitherto obtained and further .quantity of vapor at alower temperature and having less sulfuric acid than the vapors comingfrom the evaporating elements,

The annexed drawing shows dlagrammatically by way of example a verticalsection through an apparatus suitable for carrying my invention intopractice.

The apparatus comprises a number of closed elements a of suitablematerial such as cast-iron adapted to resist the. action of acids orplatinum (especially for strong acids) or ordinarily lead (for weakacids).

,The said elements are arranged in stepped order, as shown in thedrawing and'communioate with one another through pipes Z),

securing the "circulation of the acid and maintaining a constant levelin each element.

The lowermost element of the series is provided with a conduit 0 for theflowing out of the concentrated acid and the uppermost element isconnected by a conduit d to Specification of Letters Patent.

Patented Dec. 2, 1919.

a heater for the acid which is to be fed to the elements. The severalelements, three in the example shown, are further connected with eachother by conduits 7 which are provided in order to conduct the vaporsgenerated in a given element to the next upper element. As shown on thedrawing, each of the conduits 7 opens in the next upper element beneaththe level of the acid contained in the latter element. The uppermostelement, Which is fed with sulfuric. acid through the conduit d, isconnected by a conduit g to a" tubular heater "or coil 71, adapted toheat the acid which is to be concentrated.

Said tubular heater or coil h is connected to a second 0011 i placed ina cooling-vat proranged in such a manner that the concentratmg elementsa, present the greatest surface possible to the action of heating gaspro- .vided with connections is for a water-circulation. The whole ofthe apparatus is ar-- duced in a furnace Z or to any other heatingmedium. I 7

\Yhenthe apparatus is in action, the acid w'h1ch is to be concentrated,flows from the heater 6 through the conduit (1 intothe uppermost elementa of the series of elements and thence flows successively, in adescendmg course, through the conduits b in the different elementscomposing the apparatus and escapes "finally through the conduit 0.

The vapors which are produced in the lowermost element are conductedthrough the conduit f in the next upper element Where they are led, asshown by the arrow into the mass of 'liquid contained in said element.Again the Vapors produced'in the second element of the series aresimilarly conducted in the third element of the series into the mass ofliquid contained therein, and so on.

Finally the vapors produced in the last or uppermost element of theseries are conducted through the conduit g into the coil h of the heater6 where they are condensed and afterward cooled when circulating in thecoil 2' of the cooling vat It will be observed, consequently that themixture of vapors of sulfuric acid and Water, which is produced in. agiven element, is always conducted into a liquid mixture of sulfuricacid andwater having less strength or concentration than the mixturewhich has produced thesaid vapors. A condensation of the vapor ofsulfuric acid takes place consequently and the heat'which is set free bythis modification of sta.te,'again secures the vaporization of a certainquantity of water. If a condensation of a certain quantityof water-vaporalso takes place, the heat of condensation of said vapor and the heatdue to the reaction between said water of condensation and the sulfuricacid are equivalent to the quantity of heat which is neces sary for there-separation of a corresponding quantity of water and its reevaporationwith this difference, however that the new vapors, which are producedhave a temperature which is lower than that of the first mentionedvapors.

As a result, the vapors which are produced in a lower element, owing tothe fact that they are conducted into the mass of liquid contained inthe next upper element, are replaced by a corresponding quantity ofvapors having a lower temperature and less sulfuric acid thanthemselves. But as the temperature of the vapors which are produced in agiven element, is considerably lower than the boiling temperature of theliquid, the temperature of the vapors pass ing through the mass ofliquid contained in the next upper element, may be lower than theboiling temperature of said liquid. On the other hand, the vaporizationof any quantity'of water,}oth er than that corresponding to thecondensation of the vapors coming from the preceding element, requiresnot only the evaporating heat but also a new quantity of heat whichisequivalent to the heat of reaction between sulfuric acid and water.

Said quantity of heat which is necessary to secure a concentration'inthe next element,

- is furnished by the furnace Z or by any other sourceof heat, forinstance by coils heated by gas or vapor at a suitable .temperature.

These theoretical considerations show that the economical utilization oftheheat contained in the vapors which are set free and the condensationof the sulfuric acid contained in said vapors, are not necessarily boundto the passage of the vapors which are produced 1n a given element, intothe mass of-liquid contained in the next upper element but that asimilar result could be obtained by collecting together the vaporswhichare produced in the different elements of the apparatus and then leadingsaid vapors conjointly in the uppermost element in which the sulfuricacid is led for the purpose of concentration Each of the elementscomposing-the apparatus could evidently be subdivided in a number ofcompartments arranged in stepped order so as to increase the number ofpassages or bubbling of the vapors through the inass of liquid containedin each element.

-Having thus described my invention, what I claim is:

1. A method of concentrating sulfuric acid which comprises heatingseparat 1' 1- nines of acid confined against direct contact with theroducts of combustion of the source of ieat, conducting the vaporproduced by each volume of acid into acid of less concentration, thecontact of the vapor with the acid of less concentration causing theevolution of vapor containing less sulfuric acid than the vapor of theacid of higher concentration and conducting acid from one volume to thevolume of acid of greater concentration.

2. In an apparatus for concentrating sulfuric acid, a series of closedVessels each adapted to hold sulfuric acid of a'different degree ofconcentration, means for heating each of said vessels, conduitsconnecting said vessels for conducting the sulfuric acid from one vesselto the next vessel containing sulfuric acid of a greater degree ofconcentra tion,- and conduits connecting said vessels vessels forconducting the sulfuric acid from one vessel to the next vesselcontainingv sulfuric acid of a greater degree of concentration,conduitsconnecting said vessels for conductingthe vapors. given off in eachvessel to the next vessel into sulfuric acid of a less degree ofconcentratiom'a conduit for conducting weak sulfuric acid to the firstvessel of said series, a heating coil, and means for conducting thevapors from said first named vessel to said heating coil and saidheating coil being arranged to heat the Weak sulfuric acid in saidvconduit.

4. A method of concentrating sulfuric acid which comprises heatingseveral voltunes of acid to the boiling point, maintain-1 ing the acidout of contact with the products of combustion of the source of heat,conducting the vapor produced by each volume of acid into acid of lessconcentration, the contact of the vapor with the acid of lessconcentration causing the evolution of vapor containing less sulfuricacid than the vapor of the acid of higher concentration, and conductingacid from one volume to the volume of acid of greater concentration.

In testimony whereof I have aflixed my signature in presence of twowitnesses.

JAC UE BEDE, CHARLES ROY NASMITH.

